View Full Version : program issues? UNK status

07/30/2008, 11:36 AM
I am having an "unk" status after my heater, regardless of what state its actually in. Its not really a problem, as my controller is functioning fine at the moment. I had issues with my temp probe, got an RMA for a new , lost that emailand never got a new one.
I just re-plugged in my original temp probe to see what would happen, and it works fine. I needed to compensate the temp in the program, (it was off 2 degrees) but its holding temp.
SO Why am I getting unk in the status of my heater?

Here is the program I am running (yes I know I have a lot of ATO statements, but I only want my ATO kicking on when I am home.)

If Time > 16:00 Then MH1 ON
If Time > 14:00 Then FRG ON
If Time > 21:30 Then MH1 OFF
If Time > 21:30 Then FRG OFF
If Time > 14:00 Then ACT ON
If Time > 23:30 Then ACT OFF
If Time > 21:18 Then FG1 ON
If Time > 12:35 Then FG1 OFF
If Time > 05:35 Then ATO ON
If Time > 06:15 Then ATO OFF
If Time > 15:00 Then ATO ON
If Time > 15:40 Then ATO OFF
If Time > 22:00 Then ATO ON
If Time > 22:40 Then ATO OFF
If Time > 05:00 Then ATO ON
If Time > 05:50 Then ATO OFF
If Temp < 77.5 Then HET ON
If Temp > 79.0 Then HET OFF
If Temp > 84.8 Then MH1 OFF
If Temp > 83.8 Then FRG OFF
If Time > 00:00 Then RET ON
If FeedA 000 Then RET OFF
If FeedA 020 Then SKM OFF

07/30/2008, 11:49 AM
You are fine. 'UNK' is reported when then AC does not understand the state of a timer. It is nearly always seen just after an AC program restart which happens after program updates, AC reset ets. It should go away on its own.

Here is why you see it; I will start by saying there is nothing wrong with your HET program!

If Temp < 77.5 Then HET ON
If Temp > 79.0 Then HET OFF

This is your program. If the AC program is restarted and the tank temp is 78.0 the test of both statements will be false because 78 is not < 77.5 and not > 79. In this condition the AC doesn't know what to do with the HET timer so UNK is displayed. The HET timer will not be changed from what it was, on or off but it doesn't matter and here is why. If HET happened to be off then sooner or later the tank will cool off and get < 77.5 at which time the 1st statement will be true and HET will change to ON. If the HET happened to be on then sooner or later the tank temp will hit 79.1 and the second statement will become true and HET will be turned off.

Hope this helps.

07/30/2008, 11:50 AM
One note about your program; you may want to add something like the following to protect against temp probe failure:

If Temp < 75.5 Then HET OFF

07/30/2008, 11:54 AM
Thanx Ken!
I knew it wasnt effecting the program, but wanted to be sure. I have had this for almost a year now, and have barely tapped into it. Now that I have a dedicated comp for it, I expect to have many more problems.